A Brief History of Indian Orbital Rockets

Parthu

Gessler
Team StratFront
Dec 1, 2017
1,591
3,215
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Hyderabad, India
NOTE: In this compilation I'm only going to mention orbital-rated launch vehicles, as such any sub-orbital launchers/sounding rockets will not be mentioned. I'm going to divide this into two parts. The first part will cover the history up till this point, the second part will talk about where things are going.

Satellite Launch Vehicle (SLV)
1979

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After launching its first RH-series sounding rocket in 1967, ISRO (then known as INCOSPAR until 1969) set out to develop its first orbital rocket, and achieved this goal in 1979. The SLV, otherwise known by its unit designation SLV-3, was a four-stage rocket with all-solid propulsion, and was the first orbital flight-rated Indian rocket. The SLV only had 4 launches and could never develop into a successful launch system, but it had far-reaching implications for both the civilian space sector as well as the development of the Integrated Guided Missile Development Program (IGMDP) in the 80s and 90s that gave rise to Prithvi & Agni ballistic missiles.

Status: Decommissioned in 1983
Liftoff mass: 17 tons | Height: 22m | Payload to LEO: 40kg
Total launches: 4 | Success/Failure: 2/2 (50%)


Notable missions & their significance

RS-1
(18 July 1980): Rohini series of experimental spin-stabilized sats, first instance of an Indian satellite successfully being orbited by an Indian rocket | RS-D2 (17 April 1983): First Indian satellite with onboard camera, took over 2500 pictures in both visible & infrared spectrums

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Augmented Satellite Launch Vehicle (ASLV)
1987

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The ASLV was an improvement of the SLV-3 core stage accompanied by 2 additional strap-on solid boosters acting as a first-stage (taking total stages to 5), improving the payload capacity and serving as a platform for flight testing new technologies. Like the SLV that preceded it, the ASLV did not achieve commercial success but laid the technological foundation for the PSLV.

Status: Decommissioned in 1994
Liftoff Mass: 41 tons | Height: 24m | Payload to LEO: 150kg
Total launches: 4 | Success/Failure: 1/3 (25%)


Notable missions & their significance

SROSS-C2
(5 May 1994): Conducted several Gamma Ray Burst (GRB) experiments, first Indian satellite with a pure space science payload.

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Polar Satellite Launch Vehicle (PSLV)
1993

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Following liberalization of the economy in 1991, India started its growth story and by 1993, thanks to the capital infusions and the technical know-how gained over the last 15 years, ISRO was ready to pursue a large-scale program for developing a medium-class launch vehicle for the dual use of supporting India's expanding space ambitions and tapping a commercial launch market that was at the time largely dominated by the US, Western Europe & Russia.

The four-stage PSLV powered by a combination of the Vikas liquid engine and various solid boosters including S139 and PSOM SRBs was the first Indian orbital rocket that was a massive technical & commercial success, and remains continuously supported to this day by improvements in technologies, variants and continuing cost-reduction & creating a vast network of private industry to build & supply components. The PSLV allowed ISRO to pursue missions to the Moon & Mars and today, the majority of components of the PSLV are manufactured by Private companies with ISRO acting as lead integrator.

As of 2021, the PSLV & its variants including PSLV-G (original), PSLV-CA (Core Alone for lighter payloads at reduced cost) & PSLV-XL (largest capacity variant with additional strap-on boosters) launched a total of 71 Indian & 342 foreign satellites from 33 countries thanks to a mature rideshare program, putting India & ISRO on the international map as a major launch services provider with the PSLV acting as the pivotal piece of the puzzle in this turnaround, and with over 25 years of continuous operational experience & an overall success rate in the 96 percentile over 53 launches, the PSLV remains one of the most reliable & tried-and-tested launch systems currently operational in the world.

Status: Operational
Liftoff Mass: 295 tons | Height: 44m | Payload to LEO: 3800kg | Payload to GTO: 1300kg | All vehicle stats are of original PSLV, the XL variant is heavier & capable of greater payloads
Total launches: 53 | Success/Failure: 51/2 (96.3%)


Notable missions & their significance - too many to list but some of the most important are:

IRS-P2
(15 October 1994): First Indian remote-sensing satellite launched on domestic rocket, went on to form the IRS constellation, one of the biggest exclusively remote-sensing constellations in the world | CARTOSAT-1 (5 May 2005): First dual-use geocentric Earth-observation satellite of 2.5m resolution, with both civilian & strategic uses | SRE-1 (10 January 2007): Space capsule Recovery Experiment, tested the first atmospheric re-entry capable capsule with first-generation heat shield & silica tiles | Chandrayaan-1 (22 October 2008): First Indian mission to the Moon, carried an orbiter & a Moon Impact Probe (MIP) that placed the Indian Flag on the surface of Luna | RISAT-2 (20 April 2009): First Indian-built radar reconnaissance satellite with Synthetic Aperture Radar (SAR) payload | Various INSAT & GSAT series: Geostationary communication constellations | IRNSS-1A (1 July 2013): First of the IRNSS (now called NaVIC) navigation satellite constellation, Indian alternative to US GPS | MOM (5 November 2013): Mars Orbiter Mission, first ISRO interplanetary mission | Astrosat-1 (28 September 2015): First dedicated Indian Space-based observatory that made many discoveries including AUDFs01, currently one of the oldest known galaxies | PSLV-C37 (15 February 2017): With a launch of 104 satellites (majority of them American) the PSLV held the record of most sats launched on a single rocket from 2017-2021 when it was superseded by SpaceX's Falcon 9 Transporter-1 mission with 143 sats | HySIS (29 November 2018): First Indian hyperspectral imaging satellite | Microsat-R (25 January 2019): Secretive experimental sat that served as tagret for March 2019 ASAT weapon test | EMISAT (1 April 2019): First dedicated ELINT satellite | CARTOSAT-3 (27 November 2019): First of Next-gen series of EO satellites with <0.25m resolution

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Geosynchronous Satellite Launch Vehicle (GSLV)
2001

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With the success of PSLV under its belt, ISRO started on the course of attaining greater access to Geostationary orbits for the country's expanding communication satellite needs, which meant building bigger & better rockets. A key part of this included obtaining cryogenic rocket engine technology - a closely guarded tech only available with a handful of countries. Initially, while indigenous design & development continued under the Cryogenic Upper Stage Program (CUSP), ISRO decided to obtain fully-built KVD-1 engines from Russia to power the new GSLV upper stage in vacuum.

The GSLV was a 3-stage liquid-solid rocket with Vikas liquid engines powering strap-on boosters, solid S125 motor powering the core stage, another Vikas on the 2nd stage and KVD-1 cryo-engine powering the 3rd stage.

There were many problems including threat of US sanctions on Russia if they continued to supply the engines to India, leading to the supply ceasing after only 7 engines were delivered. With the limited numbers, the development of the rocket had to be optimized to the extreme as ISRO had to sparingly use the motors as they perfected the GSLV design test launch after test launch, but with the engines poorly optimized for Indian launch & weather conditions, failures were frequent. In the end the GSLV configuration as it existed (now known as Mk-1), with the Russian cryogenic engine, was never going to become a commercially viable product.

But, it allowed ISRO to perfect the launch vehicle design itself, with the only piece of the puzzle left for it to become a success was the Indian cryogenic engine - which came with the GSLV Mk-II.

Status: Decommissioned in 2010
Liftoff mass: 415 tons | Height: 49m | Payload to LEO: 5000kg | Payload to GTO: 2700kg
Total launches: 6 | Success/Failure: 2/4 (33%)


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Geosynchronous Satellite Launch Vehicle (GSLV) Mk-II
2010

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The GSLV Mk-2 is essentially the same as the Mk-1, with the only difference being that the Russian KVD-1 cryogenic engine being replaced with the indigenously designed & built CE-7.5 Cryogenic Upper Stage (CUS) staged-combustion cycle motor, developed under CUSP. With the CE-7.5 in place, India was now free to develop its geostationary orbit-class rockets as it wished, and despite a failure in the initial test flight, ISRO eventually managed to make the GSLV Mk-2 into a successful platform.

Over the course of its flights, the Mk-2 also served as a platform to validate several new propulsion technologies including the High Thrust Vikas Engine (HTVE) and the uprated C12.5 and C15 cryogenic engines.

Ironically, despite the large US hand in curtailing the early development of this class of rocket, the GSLV Mk-2 is the intended launch vehicle for the NISAR, a US-India joint project to develop the world's first Dual-band SweepSAR satellite, with a launch expected in 2022-23. With a shared development cost of $1.5 billion the NISAR is likely the most expensive Earth-imaging satellite ever built.

Status: Operational
Liftoff mass: 415 tons | Height: 49m | Payload to LEO: 5000-6500kg | Payload to GTO: 2700-3200kg
Total launches: 7 | Success/Failure: 6/1 (85%)


Notable missions & their significance

INSAT-4E/GSAT-6
(27 August 2015): First Indian-launched satellite exceeding launch mass of 2 tons | South Asia Satellite (5 May 2017): Geostationary communication & meteorological satellite providing free services to SAARC nations as a gift from India | GSAT-7A (19 December 2018): First dedicated military communication satellite for the Indian Air Force

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Geosynchronous Satellite Launch Vehicle (GSLV) Mk-III
2014

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While the GSLV Mk-2 did improve the payload capacity of ISRO launch vehicles over the earlier PSLV and could serve as a commercial launch platform going forward, it however wouldn't be enough to support India's growing ambitions of potentially building a human spaceflight-capable launch system. This gave rise to the development of the Mk-3 GSLV platform (even though called Mk-3 it had little in common with the Mk-1/2 and for this reason was also known as LVM3) supported by next-gen developments in both liquid & solid propulsion systems such as the CE-20 Cryogenic stage and the S200 solid rocket booster respectively (believed to be 3rd largest SRB in the world after the Space Shuttle's and the Ariane-5's solid boosters). The Mk-3 was also the first Indian rocket to use a clustered liquid stage with 2 x Vikas engines forming the core of the first stage.

In 2014, the Mk-3 was tested for the first time for a sub-orbital launch, and a full orbital launch in 2017 with a functioning Cryogenic stage. In all of its 4 launches so far (including Chandrayaan-2 mission) the vehicle continued to introduce new refinements to its design such as a new nose fairing, improvements to the HTVE engines among others, which allowed for a LEO payload capacity exceeding 10 tons.

A human-rated variant of the Mk-3 is the intended launch platform for India's upcoming manned spaceflight program Gaganyaan
. With a 100% success rate in the launches even in the initial testing period with many unproven technologies, the Mk-3 is inspiring confidence as a human transportation system, as well as emerging as a reliable platform for potential large-scale commercial launches.

Status: Operational
Liftoff mass: 640 tons | Height: 43m | Payload to LEO: 10,000kg | Payload to GTO: 4000kg
Total launches: 4 | Success/Failure: 4/0 (100%)


Notable missions & their significance

CARE
(18 December 2014): Crew module Atmospheric Re-entry Experiment, demonstrated the successful re-entry & recovery of a test version of the Gaganyaan crew module | GSAT-19 (5 June 2017): First Indian-launched satellite exceeding mass of 3 tons, also first to use indigenous Li-ion batteries | GSAT-29 (14 November 2018): First Indian High-Throughput communication Satellite (HTS) | Chandrayaan-2 (22 July 2019): Second Indian moon mission, this time with orbiter + lander + rover for a combined mass exceeding 3.8 tons into LTO

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Reusable Launch Vehicle-Technology Demonstrator (RLV-TD)
2016

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While the Indian space program proceeds forward with proven technologies, ISRO remains at work with various R&D programs for developing next-gen launch solutions such as re-usable spaceplane systems powered by Scramjets (among others which we will talk about in Part-2) for both civilian & strategic needs.

As part of these R&D projects, ISRO test flew a scaled-down shuttle-type spaceplane called the RLV-TD in 2016. Roughly the same size as the Boeing X-40 Space Maneuver Vehicle which served as precursor to the secretive X-37B space plane, the RLV-TD as its name suggests is intended to serve as a platform for validating various new technologies such as hypersonic flight, re-entry and autonomous runway landing under own power.

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The 2016 test, known as HEX (Hypersonic flight EXperiment) was geared toward validating the aerodynamic qualities of the fuselage as well as testing the re-entry heat tolerances of the silica tiles on the bottom of the plane as the TD made a controlled splashdown in the ocean. Although this was a sub-orbital test, its intended to develop an orbital system and the re-entry at approx Mach 5 gave tremendous amounts of data for further refining the design as a new test called LEX or Landing Experiment which will incorporate release of the plane from a helicopter and touching down with its own landing gear is scheduled for sometime this year, this will be followed by 2 more tests namely REX (Return flight) and SPEX (Scramjet Propulsion) which will fully validate the design and result in a finished product that will be much larger (estimated to be considerably bigger than even the X-37B, and approaching the Space Shuttle in size) and capable of orbiting multiple satellites (or carry astronauts) in each mission.

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The completed RLV will most likely be launched on top of a GSLV Mk3-sized first stage booster.

Status: Under development
Liftoff mass: 1.75 tons or 12 tons including booster | Height: 16m with Orbiter length of 6.5m
Total launches: 1 (success)


In Part-2 I'll go over some of the ongoing projects (which haven't been flown yet) that will shape the future of India's launch capabilities.

I'll be closing off Part-1 with this amazing photograph (and no, its not a photoshop) of the GSLV Mk-3 as it launches the Chandrayaan-2 combined orbiter-lander-rover payload into Lunar Transfer Orbit. The payloads successfully reached their destination, however the lander made a hard touchdown, crashing into the lunar surface. The orbiter, however, remains in operation, the second Indian satellite to orbit Luna after 2008's Chandrayaan-1.

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@Ashwin @Gautam @randomradio @Milspec @suryakiran
 
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Here's first portion of Part-2

NOTE: As with the preceding article, I will only be mentioning those programs that aim to develop a full-fledged orbital launch capability as their primary goal; as such programs like the Nano Satellite Launch Vehicle (NSLV) which in the opinion of this author are primarily aimed at a Sub-orbital launch capability, have been excluded.​


Small Satellite Launch Vehicle (SSLV)
2021-2022

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Diagrams from official SSLV Brochures

While ISRO's focus has rightfully been on increasing the size & payload capacity of its rockets, it hasn't forgotten the commercial & strategic implications of a small, launch-on-demand rocket system that can greatly reduce the both the cost & lead team it generally takes a put a satellite in orbit - and neither has the Government of India forgotten the strategic implications of the same technology. In 2018 the agency completed preliminary design on its SSLV platform that aimed to fulfill this emerging requirement.

In the opinion of this author, the SSLV was formulated to support two sectors, an explicitly stated civilian use centered around the rocket's reduced cost, and a so-far ambiguous military/strategic role centered around the rocket's record quick assembly time & use of solid-fuel motors for all 3 of its stages (unlike similar sized small vehicles like RocketLab's Electron which still use liquid engines).

Starting off with the civilian use-case; As the primary driving force behind the civilian launch market continues to be the cost factor, ISRO sought to reduce cost by maximizing technology commonality with the already proven PSLV & GSLV systems, considerably reducing the R&D cost for the new LV, allowing for a smaller margin for profitability, and fine-tuning the Private-sector production of components allowing for affordable expendable stages. Adding to that, the reduction in infrastructure & human resources cost thanks to the strategic imperatives of this design (which we'll go over in the next paragraph) also contributed to a planned sticker price per rocket of $4.2 million compared to $7.5 million for RocketLab's Electron.

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Various Satellite mounting options that the SSLV's onboard Payload Adapter can be configured for

The largely ambiguous strategic use-case, rarely if ever talked about by either ISRO or Department of Space but inferred by this author to be the most pivotal role & effect of this launch vehicle, is one of supposition - a result of studying its design & configuration. The SSLV is designed to be highly modular, allowing for a full rocket to be assembled & readied for launch on just a 72-hour notice - down from the usual 60 days of notice it requires a assemble a large rocket like the PSLV (or the 16 days notice it takes to get a liquid-fueled small vehicle like the Electron ready for launch) - additionally, the Command & Control of the launch is designed to be managed by lightweight software from a single PC workstation. Whereas the PSLV took a workforce of 600 staff in the Vehicle Assembly Building (VAB) to put the rocket together, the small modular SSLV is designed to require only 6 people to complete its assembly, plus as per statements of the Chairman of ISRO, development of mobile launch solutions for the SSLV is also underway (offshore platform development confirmed, eventual use of land-mobile Transporter Erector Launcher (TEL) type vehicle for SSLV or some future version of it again inferred by the author). Similar in scope to the Chinese Long March-11 (offshore) & Kuaizhou-11 (road-mobile) rockets.

Assembly by a skeleton crew on short notice using modular components thanks to exclusion of liquid-fueled stages, C&C designed to accommodate field use without necessarily having access to extensive control facilities, or the ability to launch from austere conditions away from established launch pads all point toward a military-strategic nature of the system, very likely a requirement meant to be fulfilled by the newly formed Defence Space Agency (DSA), geared toward quickly re-establishing a limited satellite-based capability set on a short notice (to include navigation, earth observation, radar & infra-red reconnaissance, ELINT/SIGINT among other tactical uses) - in the event of existing long-term space assets being knocked out by an adversary's ASAT weapons in a first-strike scenario.

The SSLV is currently undergoing static tests on its various stages & solid rocket motors, the first launch is expected sometime this year - it will be carrying the Microsat-2A payload (renamed to EOS-02 under the new broad-based ISRO naming scheme for satellites) on its first Demo flight.

Status: Static Stage Testing
Liftoff mass: 120 tons | Height: 34m | Payload to LEO: 500kg | Payload to SSO: 300kg

Intended Objectives
Affordable access to space for smaller & lighter payloads, supported by more frequent launches | Possible strategic use as a means of re-establishing critical space-based services in the event of hostile Anti-Satellite action


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Advanced Mission & Recovery Experiments (ADMIRE)
2021-2025​

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From a presentation by Dr. S. Somanath of Vikram Sarabhai Space Centre (VSSC), detailing various technologies being developed to support the reusable stage program

While its chief R&D activities continue to be on the front of next-gen propulsion systems for both rockets & hypersonic spaceplanes, as they should considering the fact they remain a state-run enterprise, ISRO isn't blind to the advantages of re-usable vertical takeoff & vertical landing (VTVL) rockets a-la SpaceX Falcon 9 and the value they bring to the commercial launch market - and the need to develop similar technologies for Indian launchers. The ADMIRE program aims to do just that. While its not known in the public domain what exactly the acronym stands for, its popularly believed to mean "Advanced Mission & Recovery Experiments" - either way, its clear what it aims to achieve: Development, demonstration & eventual commercialization of a liquid-fueled booster stage that can take off vertically like a normal rocket, and after seperation autonomously guide itself back to a designated LZ and land under its own power.

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ADMIRE booster with its landing legs deployed

While the initial ADMIRE boosters themselves will be small, the focus will be on the software end, on developing the guidance & sensor package that will allow creation of a VTVL booster. The technology will then be scaled up and potentially applied to all liquid-fueled ISRO rockets performing commercial launch operations - incurring further cost reductions that way.


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Private-sector Launchers
2022​

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Artist render of Skyroot Aerospace's Vikram-I Launch Vehicle


Since around 2015, several private-sector start-ups have sought a piece of the multi-billion space industry pie by focusing on various niche technology fields such as in-space satellite propulsion, satellite-based services, and more recently following liberalization of the laws & regulations surrounding the space sector in 2019, privately-developed launch vehicles.

For the purposes of this article, I'm gonna be focusing on three of the more prominent private companies currently engaged in some form of launch vehicle or related technology development. Namely Skyroot Aerospace, Agnikul Cosmos & Bellatrix Aerospace.

Skyroot, founded by a group of ex-ISRO scientists & funded to the tune of $15 million by several Indian & foreign investors and with the support of several top ISRO personnel in advisory positions is currently the best-placed organization to develop a private-sector launch capability in the form of their Vikram-series of small satellite launchers.

Vikram-I, the first in line to be developed is intended to have a payload capacity of 315kg to LEO & 225kg to SSPO - in the same overall payload class as the RocketLab Electron. But with all-solid propulsion, 3D-printed components & modular design, Skyroot is aiming for a 24-hour assembly period (making it a potential pitch for the DSA as well). This will be followed by the Vikram-II with a Cryogenic Methalox upper stage boosting the payload capacity to 520kg LEO/410kg SSPO, and finally the Vikram-III with the same Cryo engine supported by additional solid rocket boosters in the first stage, taking payloads to 720kg LEO/580kg SSPO.


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Skyroot's Dhawan-1 (top) & Agnikul's Agnilet (bottom) 3D-printed liquid engines


Skyroot tested their Raman liquid-fueled Orbital Adjustment Module (for velocity-trimming of the payload section) in August 2020, followed by the Kalam-5 solid rocket motor in December 2020, and the LNG/LoX-fueled Dhawan-1 cryogenic engine was also unveilved last year. The cryo stage intended for Vikram-II & III will allow for multi-orbit placement of satellite payloads. Skyroot expects the first launch of Vikram-I sometime in 2022.

Agnikul Cosmos, a startup incubated at the IIT-Madras university's NCCRD (National Centre for Combustion Research & Development) and backed by $11 million in Series-A funding is focusing on smaller liquid-fueled rockets. Their 2/3-stage (depending on configuration) Agnibaan rocket is designed to have a LEO payload capacity of 100kg. In February 2021, their Kerolox-fueled Agnilet semi-cryogenic 2nd stage motor was test fired. This will be followed by tests of the Agnite first-stage motor sometime this year. The Agnibaan's first stage will comprise of 7 clustered Agnite engines each producing 25kN of thrust. Angikul is also aiming for full road-mobility of the rocket's carrier vehicle. First launch of this system is also expected in 2022.

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Agnibaan by Agnikul Cosmos

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Bellatrix Garuda

Which brings us to Bellatrix - a startup primarily focused on in-space satellite propulsion with their May 2021 test of India's first privately-developed Hall-effect thruster, also deserves a mention in this list. Although they do have plans for launch vehicles of their own - namely the 12-ton 150kg SSO Chetak and 43-ton 1000kg SSO Garuda, their focus for the immediate future remains development of the Bellatrix Aerospace Orbital Transportation Vehicle (OTV) - now named Pushpak, a 'space taxi' similar in profile to the American Momentus Vigoride. The OTV is powered by 4 x 200W Hall thrusters and allows for even smaller launch vehicles to send payloads into Geostationary orbits by providing continous propulsion in space long after the rocket itself is spent. The OTV has been contracted by Skyroot Aerospace to be used on their Vikram-series launchers.


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CGI of Bellatrix Aerospace OTV (Orbital Transportation Vehicle) made by Youtuber Gareeb Scientist

Both Skyroot & Agnikul are currently targeting the small launch vehicle sector as that's the area with the most clear-cut way to profitability at this stage and with their current levels of investment.

Continued...​
 
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Part-2 continued

Human-rated GSLV Mk-III
2022


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GSLV Mk-3 with Gaganyaan capsule by Harshal Pal

A human-rated (HR) variant of the Mk-3 GSLV is envisaged for the Gaganyaan missions. The core stage, cryogenic stage & solid boosters of the HR Mk-3 are essentially the same as the regular version, but with certain design changes introduced to increase its slated reliability, and with every component, nut & bolt tested & qualified to a much higher standard considering the fact that the astronauts' lives depend on it.

The chief difference will of course be the large Orbital Module (comprised of the Crew Module that carries 3 astronauts & the Service Module) and the large Crew Escape System (validated in a Pad Abort Test in 2018) that sit on top of the Cryogenic stage in place of the regular payload fairing.

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Configuration of Orbital Module on the Mk-3 GSLV

The process of human-rating the Mk-3 GSLV officially began in November 2020.

The first developmental launch of the Mk-3HR, Gaganyaan-1 mission, was expected in late 2021 but has apparently slipped into 2022, it will be followed by a 2nd developmental flight in the same year, and finally culminating in the crewed Gaganyaan-3 mission currently scheduled for sometime in 2023.

Until the MLV family of launchers (next in line in this article) are perfected, the Mk-3HR will continue to be the go-to human transportation system for Indian astronauts in all following missions.

Status: In Process of Human-rating
Liftoff mass: 640 tons | Height: 45m | Payload to LEO: 10,000kg

Intended Objectives
First human spaceflight-capable Indian rocket | Sustaining manned access to space


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Modular Launch Vehicle (MLV) Family
2025-2030

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Indian Space Transportation System Roadmap (underwent several iterations since this slide was released)

The MLV is the successor program for ISRO's plan for a Unified Launch Vehicle (ULV) project which existed in one way or the other on the drawing board since before 2013. Much like how the PSLV hinged on the Vikas liquid engine and the GSLVs hinged on India's development of an indigenous cryogenic engine, the MLV program hinges on the development of the SCE-200 - a large staged-combustion semi-cryogenic engine producing upwards of a massive 2,000kN of thrust. To put it in perspective, that's more than twice the thrust produced by SpaceX's Merlin 1D engine that powers the Falcon 9 & Falcon Heavy.

The SCE-200's design is heavily based on the RD-810 of Ukraine's Yuzhnoye Design Bureau which had a hand in Soviet rocket engine development pre-1991. However, even though they sold the design, considering Yuzhnoye never actually built any engines based on this design before, much of the engineering models had to be developed, tested & perfected by ISRO & subcontractor Godrej Aerospace themselves, throwing a spanner into any hope for a short development time. The RD-810 traces its lineage back to the original Soviet RD-120 engine family - of which the Chinese YF-100 & YF-115 that power some of China's biggest rockets, are also members - but none are as big or powerful as the SCE-200.

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ISRO is currently in the process of building new static test sites for performing sea-level test-fires of the engine - indicating maturity of the design & development process to a satisfactory level.

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SCE-200 in Single & Clustered Configuration

The MLV family which will use this engine in both single & clustered configurations, comprises of medium to heavy launchers built around the same engines, same stages, and maximum commonality between rockets in both hardware & software aspects to reduce cost and streamline production. As shown in the slide above, the smallest member of the family could have a modest capacity of 11 tons to LEO and 5 tons to GTO (not much different from the current Mk-3 GSLV) and scales up to a Heavy-class that uses clustered core & clustered boosters to lift 16 tons to GTO and a cool 41 tons to LEO (estimates increased to 52 tons in more recent official graphics) - larger than Europe's biggest planned launcher Ariane 64 and approaching Falcon Heavy.

The MLV family will form the core of ISRO's future commercial & human spaceflight missions and contribute toward a sustained Indian human presence in space, plans for a space station, and more. The first static test-firing of the engine is expected this year or the next, with the first launches of rockets powered by actual SCE-200 stages expected toward the middle of this decade, and operationalization of the full MLV family by around 2030.

The long-term future of ISRO & India's space ambitions ride on the SCE-200 family, future variants of the Cryogenic engine family (C32 and so on), and the MLV program - the building blocks for a robust space access system.

Status: Under Development
Liftoff mass: 300-1,000 tons (est.) | Height: ~45-75m (est.) | Payload to LEO: 11-52 tons | Payload to GTO: 5-16 tons

Intended Objectives
Streamlined design & production across medium & heavy launch vehicles with maximum systems commonality | Expanding scope of payloads to include large crew modules for advanced space exploration & robotic interplanetary missions | Sustaining Indian manned & unmanned access to space in the decades to come


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Two-Stage To Orbit (TSTO) Program
2016-2030​

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The TSTO-TD is not unlike some NASA-AFRL studies into Reusable Two-Stage To Orbit Hypersonic spaceflight

The RLV-TD mentioned in Part-1 is one among many technology-demonstration efforts that feed into ISRO's overarching program to develop Two-Stage To Orbit (TSTO) reusable flight capability that leverages a combination of air-breathing Scramjets & rocket engines.

The first step began with the August 2016 test of the Scramjet-TD which launched on a sounding rocket and achieved speeds of Mach 6 before splashing down in the sea. The RLV-TD testing program which also began the same year was focused on validating the various airframes & aerodynamic data required for the project to progress. ISRO remains at work to further develop the Scramjet demonstrators, a new design meant to achieve speeds of Mach 7 was revealed in 2019 and several programs came to light since then.

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CAD model of HAVA demonstrator

Notably the Hypersonic Air-breathing Vehicle Airframe-integrated structure (HAVA), designed for Mach 6-7 envelop meant to launch on top of a rocket was unveiled and is expected to be tested in the coming years. These developmental programs would culminate in the planned TSTO-TD HOTOL (horizontal take-off & landing) vehicle (pictured below) powered by a combination of Turbo-Ramjets, Scramjets & Rockets to achieve a full flight envelop ranging from Mach 0 to Mach 12 and capable of throwing a 2-ton payload into LEO.

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Diagram of TSTO-TD with intended flight trajectory & specifications, shared by Dr. S. Somanath of VSSC

While the ultimate, larger production vehicle that would likely emerge from these programs is as of yet unknown, hazarding an educated guess gives us a cross between the Space Shuttle and the Reaction Engines' Skylon concept.

While the civilian aspects of these programs are all well and good, we cannot forget the strategic implications and cross-pollination of these technologies which have applications in everything from Hypersonic Glide Vehicles (HGVs) mounted on rocket boosters to X-37B-esque spaceplanes that can snatch-and-grab foreign satellites and bring them home to study.

Status: Technology Demonstration & Proof-of-Concept Testing

Intended Objectives

Maximizing re-usability & cost-effectiveness by eliminating the need to have expendable stages | Enabling sub-conventional (covert/clandestine) options for dealing with hostile space assets


To sign off...​

Moonshot Rockets
2030-2040

roadmap.JPG

"The Way Forward to 2050" - A roadmap of the long-term goals of ISRO shared by official sources

Since long, there has been talk of a Super-Heavy (by Soviet standards) class of launch vehicle from ISRO (with LEO payloads exceeding 100-150 tons and ~50 tons to Trans-Lunar Injection), aimed at a Moonshot capability for long-term space exploration & potential colonization, at the same level as the erstwhile Saturn V or China's upcoming Long March 9.

As of now, this remains speculation and while its true that ISRO holds long-term plans for all that & more, at present it cannot be said that a Moonshot rocket is on the immediate wish-list for India.

But its definitely something to aim for.